I had a call today at a waste treatment plant (glamorous life of an A/C & Refrigeration man). The call was for a water-sampling unit a small refrigerator with a water jug in it. Periodically a small sample of wastewater is dumped in and collected over a twenty-four hour period. Then the container is changed and the water sent for testing.
EPA guidelines require the sample be kept at 0-5º Celsius. The unit is charged with 4.5 oz 406a? Some miracle blend that replaces R-12. The unit has a cold plate with no fan that keeps icing. Also has a Ranco differential stat I am unfamiliar with. It had no number. It has a dial on top that sets the target temp on a sliding scale. Beneath this dial is a small round plate with two arrows on it. One arrow says nothing and when pointing at a dot on top of the stat adjusts the temp scale. One arrow says diff and when turned to this arrow the knob will adjust three or four turns, but has no scale to read. Anyone familiar with this control that knows how to set the differential?
While there I saw a row of pumps that piqued my interest. The motor on one of these babies had a rating of 1260 HP at 4120 Volts 190 Amps. That bad boy was six feet tall and four feet in diameter. The operator told me that was the small one; it pumped 30 million gals a day. Thats a lot of poopy.